Lamp driving apparatus, backlight assembly and liquid crystal display device using the same

ABSTRACT

In a lamp driving apparatus, backlight assembly and liquid crystal display device using the same, the lamp driving module is mounted on the substrate and provides lamps with power voltage. Sensors are disposed on the substrate to face the lamps, and detect operation state of the lamps to output sensing signals. Voltage cut-off module is disposed on the substrate and compares the sensing signals with a predetermined reference signal. The voltage cut-off module provides the lamp driving module with voltage cut-off signal when at least one of the sensing signals has an amplitude smaller than the reference signal. The deterioration of the lamps may be prevented, and the life expectancy of lamps except broken lamps may be increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 10/629,056 filed Jul. 28, 2003, now U.S. Pat. No. 7,126,575 whichclaims priority to Korean Patent Application No. 2003-13178, filed onMar. 3, 2003, and all the benefits accruing therefrom under 35 U.S.C.§119, the contents of which in its entirety are herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lamp a driving apparatus, a backlightassembly and a liquid crystal display device using the same.

2. Description of the Related Art

A liquid crystal display (LCD) device is a flat panel display device anddisplay an image by means of liquid crystal. The liquid crystal changesa transmissivity of light passing through the liquid crystal accordingto an electric field applied to the liquid crystal.

However, since the liquid crystal is not able to generate light, theliquid crystal display device employs lamps so as to display imagesunder dark environment. The liquid crystal display device having a smallscreen size employs one or two lamps so as to display images.

According as the screen size of the liquid crystal display deviceincreases, the liquid crystal display device employs a plurality oflamps, for example 10˜20 lamps. In addition, some liquid crystal displaydevice employs lamps arrange in parallel.

However, when the liquid crystal display device employs a plurality oflamps, the cost for manufacturing the liquid crystal display device, theweight and size of the liquid crystal display device greatly increasessince the number of lamp driving apparatus also increase according tothe increase of the number of the lamps.

In order to reduce the number of the lamp driving apparatus, the liquidcrystal display device employs the lamps, each of which is parallelconnected, arranged in parallel and one or two lamp driving apparatusfor turning on or turning off the lamps simultaneously.

The conventional liquid crystal display device may reduce the number ofthe lamp driving apparatus, but the life expectancy of the other lampsexcept broken lamps may be reduced and the other lamps may be damagedbecause over current may be flow through the other lamps when one of thelamps are broken down.

SUMMARY OF THE INVENTION

Accordingly, it is one aspect of the present invention to provide a lampdriving apparatus, which provides parallel connected lamps with powervoltage, detects abnormal operation of the lamps, and prevents the powervoltage from being supplied to the lamps so as to protects the lampswhen at least one of the lamps operates abnormally.

It is another aspect of the present invention to provide a backlightassembly employing above lamp driving apparatus.

It is further another aspect of the present invention to provide aliquid crystal display device having above backlight assembly.

In one aspect of the present invention, there is provided a lamp drivingapparatus. The lamp driving apparatus includes a plurality of lampsarranged in parallel, a substrate facing the lamps, a lamp drivingmodule, a plurality of sensors and a voltage cut-off module. The lampdriving module is mounted on the substrate and provides the lamps with apower voltage. The sensors are disposed on the substrate to face thelamps, and detect an operation state of the lamps to output a pluralityof sensing signals. The voltage cut-off module is disposed on thesubstrate, and compares the sensing signals with a predeterminedreference signal. The voltage cut-off module provides the lamp drivingmodule with a voltage cut-off signal to prevent the lamp driving modulefrom providing the lamps with the power voltage when at least one of thesensing signals has an amplitude smaller than the reference signal.

In another aspect of the present invention, there is provided abacklight assembly comprising a lamp assembly, a receiving container anda lamp driving device. The lamp assembly includes a plurality of lampsarranged in parallel, each of the lamps has a first electrode formed ata first end and a second electrode formed at a second end, and the lampassembly provides the lamps with a power voltage to turn on or turn offthe lamps. The receiving container receives the lamp assembly, and has aplurality of openings facing each of the lamps. The lamp driving deviceincludes i) a substrate facing the receiving container, ii) a lampdriving module, mounted on the substrate, for providing the lamps withthe power voltage, iii) a plurality of sensors, disposed on thesubstrate to face the lamps, for detecting an operation state of thelamps to output a plurality of sensing signals, iv) a voltage cut-offmodule, disposed on the substrate, for comparing the sensing signalswith a predetermined reference signal. The voltage cut-off moduleprovides the lamp driving module with a voltage cut-off signal toprevent the lamp driving module from providing the lamps with the powervoltage when at least one of the sensing signals has an amplitudesmaller than the reference signal.

In further another aspect of the present invention, there is provided aliquid crystal display device comprising a backlight assembly and aliquid crystal display panel assembly. The backlight assembly includesi) a lamp assembly including a plurality of lamps arranged in parallel,each of the lamps having a first electrode formed at a first end and asecond electrode formed at a second end, the lamp assembly providing thelamps with a power voltage to turn on or turn off the lamps, ii) areceiving container for receiving the lamp assembly, the receivingcontainer having a plurality of openings facing each of the lamps, iii)a lamp driving device including iii-1) a substrate facing the receivingcontainer, iii-2) a lamp driving module, mounted on the substrate, forproviding the lamps with the power voltage, iii-3) a plurality ofsensors, disposed on the substrate to face the lamps, for detecting anoperation state of the lamps to output a plurality of sensing signals,iii-4) a voltage cut-off module, disposed on the substrate, forcomparing the sensing signals with a predetermined reference signal, thevoltage cut-off module providing the lamp driving module with a voltagecut-off signal to prevent the lamp driving module from providing thelamps with the power voltage when at least one of the sensing signalshas an amplitude smaller than the reference signal. The liquid crystaldisplay panel assembly is mounted on the receiving container, anddisplays an image using a light generating from the lamps.

As described above, according to the liquid crystal display device ofthis invention, the sensors for detecting the operation state of thelamps are installed in the lamp driving apparatus. The lamp drivingapparatus may detect the abnormal operation of the lamps.

Therefore, the cost for manufacturing the liquid crystal display devicemay be reduced, and the life expectancy of the other lamps except brokenlamps may be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail the preferredembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic view showing a lamp driving apparatus according toa first exemplary embodiment of the present invention;

FIG. 2 is a schematic view showing a lamp assembly and the lamp drivingapparatus of FIG. 1;

FIG. 3 is cross-sectional view taken along the line A-A of FIG. 2;

FIG. 4 is a graph showing a sensing signal outputted from a conductivemember of the lamp driving apparatus of FIG. 1;

FIG. 5 is a perspective view showing a distance regulation member forregulating a distance between the lamps and the. conductive member ofFIG. 1;

FIG. 6 is a schematic view showing a lamp driving apparatus according toa second exemplary embodiment of the present invention;

FIG. 7 is partial perspective view showing a light interferenceprotection member of the lamp driving apparatus of FIG. 6;

FIG. 8 is a schematic view showing a lamp driving apparatus according toa third exemplary embodiment of the present invention;

FIG. 9 is an exploded perspective view showing a first exemplaryembodiment of a backlight assembly according to the present invention;

FIG. 10 is an exploded perspective view showing a second exemplaryembodiment of a backlight assembly according to the present invention;

FIG. 11 is an exploded perspective view showing a third exemplaryembodiment of a backlight assembly according to the present invention;and

FIG. 12 is an exploded perspective view showing an example of a liquidcrystal display device according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

Embodiment 1 of Lamp Driving Apparatus

FIG. 1 is a schematic view showing a lamp driving apparatus according toa first exemplary embodiment of the present invention, and FIG. 2 is aschematic view showing a lamp assembly and the lamp driving apparatus ofFIG. 1.

Referring to FIG. 1, the lamp assembly 200 includes a plurality of lamps100 and a module 160. The lamp driving apparatus 300 supplies powervoltage to the lamp assembly 200.

Referring to FIG. 2, each of the lamps 100 includes a lamp body 110, afirst electrode 120 and a second electrode 130. For example, the lampmay be a cold cathode fluorescent lamp (CCFL). The first electrode 120is disposed at a first end of the lamp, and the second electrode 130 isdisposed at a second end of the lamp.

At least two lamps are arranged in parallel. Each of the lamps has alength L1, and the total width of the lamps 100 is W1.

The module 160 is parallel connected to the lamps arranged in parallel.The module 160 includes a first module 140 and a second module 150. Thefirst module 140 is parallel connected to the first electrodes 120 ofthe lamps arranged in parallel, and the second module 150 is parallelconnected to the second electrodes 130 of the lamps.

The lamp driving apparatus 300 supplies the power voltage to the lamps100 through the module 160 so as to turn on or turn off the lamps 100.

Hereinafter, the lamp driving apparatus 300 is explained in detail.

Referring to FIGS. 1 and 2, the lamp driving apparatus 300 includes asubstrate 310, a lamp driving module 320, sensors 330 and a voltagecut-off module 340.

FIG. 3 is cross-sectional view taken along the line A-A of FIG. 2.

Referring to FIGS. 2 and 3, the substrate 310, for example, may be aprinted circuit board. The substrate 310 has a shape of rectangularparallelepiped plate that has a first face 301 and a second face 303,and disposed under the lamps 100 to face the lamps 100. A length L2 ofthe substrate 310 is larger than the W1. The first face 301 of thesubstrate 310 faces the lamp assembly 200, and the second face 303 ofthe substrate 310 faces the first face 301.

For example, the substrate 310 may be disposed between the firstelectrode 120 and the second electrode 130. The substrate 310 may bedisposed adjacent to the first electrode 120 or adjacent to the secondelectrode 130.

Referring again to FIGS. 1, 2 and 3, the lamp driving module 320 ismounted on the substrate 310. The lamp driving module 320 outputs thepower voltage to the module 160. The lamp driving module 320 raises thevoltage level from a first voltage, which is ranged from a few volts toa few hundred volts, to a second voltage that is ranged from a few kV totens of kV. The lamp driving module 320 generates the power voltage, butalso controls the frequency of the power voltage signal. In addition,the lamp driving module 320 the point of time when the power voltagesignal is applied to the lamps 100. The lamp driving module 320 may bedisposed on a second face 303 of the substrate 310.

The sensors 330 are mounted on a first face 301 of the substrate 310.For example, each of the sensors 330 is disposed under each of the lamps100 such that each of the sensors 330 respectively corresponds to eachof the lamps 100.

Each of the sensors 330 may be a conductive member 336. For example, theconductive member 336 comprises a metal such as copper. A magnetic fieldgenerated from the lamps 100 induces a current on the conductive member336 according to an electromagnetic induction phenomenon. Accordingly,the conductive member 336 detects the operation state of the lamps 100and outputs the induced current as a sensing signal 332.

The sensing signal 332 may be changed according to the operation stateof the lamps 100. For example, the sensor disposed under the lampoperating normally outputs a sensing signal having maximum amplitude.The sensor disposed under the lamp operating abnormally outputs asensing signal having minimum amplitude. The amplitude of the sensingsignal may be decreases according as the degree of the abnormality ofthe lamps increases.

FIG. 4 is a graph showing a sensing signal outputted from a conductivemember of the lamp driving apparatus of FIG. 1.

Referring to FIGS. 1 and 4, x axis represents time axis, y axisrepresents a signal level of the sensing signal 332. The signal level ofthe sensing signal 332 has a maximum value at initial point of the graphsince a lamp operates normally at initial point. The lamp may operateabnormally after the lamp is used for a long time. The operationcharacteristic of the lamp may be deteriorated according as theoperation hours of the lamp becomes longer, so that the signal level ofthe sensing signal 332 decreases.

A graph ‘b’ represents a reference signal level. The reference signallevel has a constant value regardless of time. When the signal level ofthe sensing signal 332 is larger than the reference signal level, it isestimated that the lamp operates normally. When the signal level of thesensing signal 332 is smaller than the reference signal level, it isestimated that the lamp operates abnormally.

The farther is from the lamp, the less is the intensity of the magneticfield. Accordingly, when the distance between the lamp and theconductive member 336 is too far, the signal level of the sensing signaloutputted from the conductive member 336 may be smaller than thereference signal level even though the lamp disposed over the conductivemember 336 operates normally. In addition, when the distance between thelamp and the conductive member 336 is too close, the signal level of thesensing signal outputted from the conductive member 336 may be largerthan the reference signal level.

Therefore, for example the distance between the conductive member 336and the lamp disposed over the conductive member 336 may be in a rangefrom about 3 mm to about 5 mm.

FIG. 5 is a perspective view showing a distance regulation member forregulating a distance between the lamps and the conductive member ofFIG. 1.

Referring to FIG. 5, a distance regulation member 308 is mounted on thefirst face 301 of the substrate on which the conductive member 336 isformed along the circumference of the substrate 310. The distanceregulation member 308 regulates the distance between the lamp and theconductive member 336.

The distance regulation member 308 has a shape of a rectangular frame.The distance regulation member 308 may have a pillar (or post) shape tobe disposed on the first face 301 of the substrate 310. The distancebetween the lamp and the conductive member 336 may be regulated to be inthe range from about 3 mm to about 5 mm. The distance regulation member308 comprises an insulation material so as to prevent the conductivemember 336 of the substrate 310 from being electrically short with otherconductive material.

Referring again to FIG. 1, the voltage cut-off module 340 is disposed onthe substrate 310. The voltage cut-off module 340 receives the sensingsignal 332 outputted from the sensors 330. The voltage cut-off module340 compares the reference signal level and the signal level of thesensing signal 332, and a voltage supply signal 342 and a voltagecut-off signal 344 depending on the result of the comparison.

Particularly, the voltage cut-off module 340 receives the sensingsignals 332 outputted from all of the sensors 330. The voltage cut-offmodule 340 compares the reference signal level and the signal level ofthe sensing signal 332, and provides the lamp driving module 320 withthe voltage supply signal 342 so that the lamp driving module 320applies the power voltage to the lamps 100 when all of the signal levelsare larger than the reference signal levels. Accordingly, all of thelamps 100 are turned on by the power voltage applied from the lampdriving module 320.

The voltage cut-off module 340 provides the lamp driving module 320 withthe voltage cut-off signal 344 so that the lamp driving module 320 doesnot apply the power voltage to the lamps 100 when at least one signallevels of the sensing signals 332 are smaller than the reference signallevels. Accordingly, all of the lamps 100 are turned off by the lampdriving module 320 in order to prevent overcurrent from flowing into thelamps that operates normally.

The voltage cut-off module 340 is connected to the lamp driving module320 and the alarm 345 mounted on the substrate 310. The alarm 345 startsan alarm operation in response to the voltage cut-off signal 344 when atleast one lamp operates abnormally. The alarm 345 may alarm with a voiceor a sound.

According to above embodiment, the lamp driving module applies powervoltage to the lamps arranged in parallel to turn on or turn off thelamps, and each of the sensors detects the operation state of thecorresponding lamp. The voltage cut-off module compares the referencesignal level and the signal level of the sensing signals outputted fromthe sensors, prevents the lamp driving module from applying the powervoltage to the lamps when at least one signal levels of the sensingsignals are smaller than the reference signal levels, so that the lampsoperating normally may be protected from the overcurrent flowingthrereinto.

Embodiment 2 of Lamp Driving Apparatus

FIG. 6 is a schematic view showing a lamp driving apparatus according toa second exemplary embodiment of the present invention. In theembodiment 2 of lamp driving apparatus, other elements except thesensors are the same as those of the embodiment 1, the same referencenumerals denote the same elements of embodiment 1, and thus the detaileddescriptions of the same elements will be omitted.

Referring to FIG. 6, the sensors 350 are mounted on a first face 301 ofthe substrate 310. For example, each of the sensors 350 is disposedunder each of the lamps 100 such that each of the sensors 350respectively corresponds to each of the lamps 100.

The sensors 350 generate sensing signals 356 in accordance with theoperation state of the lamps 100. The sensing signals 356 may be changedaccording to the operation state of the lamps 100. For example, thesensor disposed under the lamp operating normally outputs a sensingsignal having maximum amplitude. The sensor disposed under the lampoperating abnormally outputs a sensing signal having minimum amplitude.The amplitude of the sensing signal may decrease according as the degreeof the abnormality of the lamps increases.

Each of the sensors 330 is a photoelectric sensor for transducing thelight generated from the lamps to a current signal according to aphotoelectric effect phenomenon to output the sensing signal. Forexample, the sensors 350 may include a conductive member 354 and anamorphous silicon thin film 352. For example, the conductive member 354comprises a metal, and the amorphous silicon thin film 352 is depositedon an upper surface of the conductive member 354 by a chemical vapordeposition (CVD). The sensors 350 having the amorphous silicon thin film352 deposited on the conductive member 354 is disposed on the first face301 of the substrate 310 such that each of the sensors 350 respectivelycorresponds to each of the lamps 100.

A portion of the conductive member 354 is electrically connected to thevoltage cut-off module 340 so as to output the sensing signal 356.

The sensor 350 generates the sensing signal 356 in response to quantityof the light perpendicularly incident into the sensor 350.

When the distance between the lamp 100 and the sensor 350 is very closeand the quantity of the light incident into the sensor is very large,the sensor disposed under the lamp operating abnormally may receive thelight generated from the lamp operating normally. In addition, when thedistance between the lamps is very close and the quantity of the lightincident into the sensor is very large, the sensor disposed under thelamp operating abnormally may receive the light generated from the lampoperating normally.

In this case, the signal level of the sensing signal generated from thesensor disposed under the lamp operating abnormally is similar to thatof the sensing signal generated from the sensor disposed under the lampoperating normally.

FIG. 7 is partial perspective view showing a light interferenceprotection member of the lamp driving apparatus of FIG. 6.

Referring to FIG. 7, the light interference protection member 357 isdisposed at the circumference of the sensor 350. The sensor 350 issurrounded with the light interference protection member 357. The lightinterference protection member 357 includes a plurality of sidewalls357a surrounding the circumference of the sensor 350. The lightinterference protection member 357 has an opening though which the lightgenerated from the lamp is incident into the sensor 350. The lightinterference protection member 357 prevents the sensor from beingaffected by the lamps adjacent to the lamp disposed over the sensor.

The sensing signals 356 generated from the sensors 350 are applied tothe voltage cut-off module 340. The voltage cut-off module 340 comparesthe reference signal level and the signal level of the sensing signal356. The voltage cut-off module 340 provides the lamp driving module 320with the voltage supply signal 342 so that the lamp driving module 320applies the power voltage to the lamps 100 when all of the signal levelsare larger than the reference signal levels. Accordingly, all of thelamps 100 are turned on by the power voltage applied from the lampdriving module 320.

The voltage cut-off module 340 provides the lamp driving module 320 withthe voltage cut-off signal 344 so that the lamp driving module 320 doesnot apply the power voltage to the lamps 100 when at least one signallevels of the sensing signals 356 are smaller than the reference signallevels. Accordingly, when the voltage cut-off signal 344 is applied tothe lamp driving module 320, all of the lamps 100 are turned off by thelamp driving module 320.

According to the embodiment 2, the operation state of a lamp is detectedby a sensor using the quantity of the light generated from the lampdisposed over the sensor when the distance between the lamp and thesensor is too far or too close for the sensor to exactly detect theoperation state of the lamp.

Embodiment 3 of Lamp Driving Apparatus

FIG. 8 is a schematic view showing a lamp driving apparatus according toa third exemplary embodiment of the present invention. In the embodiment3 of the lamp driving apparatus, other elements except the sensors arethe same as those of the embodiment 2, the same reference numeralsdenote the same elements of embodiment 2, and thus the detaileddescriptions of the same elements will be omitted.

Referring to FIG. 8, the sensors 360 generate sensing signals 366 inaccordance with the quantity of the light generated from the lamps 100.The sensing signals 356 may be changed according to the operation stateof the lamps 100.

Each of the sensors 360 includes a photoelectric device for transducingthe light generated from the lamps to a current signal by a photovoltaiceffect. For example, the sensor 360 includes a photodiode or aphototransistor. The photodiode or the phototransistor has a thin filmshape.

The sensors 360 are mounted on a first face 301 of the substrate 310.For example, each of the sensors 360 is disposed under each of the lamps100 such that each of the sensors 360 respectively corresponds to eachof the lamps 100.

A power voltage Vcc is applied to a first electrode 362 of the sensor360, and a second electrode 364 of the sensor 360 is connected to thevoltage cut-off module 340. The power voltage Vcc is applied to thefirst electrode 362 of the sensor 360 through a signal line 368 by thelamp driving module 320. When the sensor 360 is a phototransistor, forexample, the first electrode 362 may be an emitter electrode of thephototransistor, and the second electrode 364 may be a collectorelectrode of the phototransistor. When the light of which intensity islarger than a predetermined value is applied to the base electrode ofthe phototransistor, the threshold voltage of the phototransistor islowered, and current is able to flow from the emitter electrode 362 tothe collector electrode 364. Accordingly, the power voltage Vcc appliedto the emitter electrode 362 is also applied to the collector electrode364. The sensing signal 366 is outputted from the collector electrode364.

In case the sensor 360 is a photodiode, when a reverse voltage isapplied to the PN junction of the photodiode and the light of whichintensity is larger than a predetermined value is incident into the PNjunction, the photodiode is turned on to output the sensing signal 366.

The voltage cut-off module 340 receives the sensing signal 366 outputtedfrom the second electrode 364 and determines the operation state of thelamp. The sensor disposed under a lamp operating normally outputs asensing signal having a high level. However, the sensor disposed under alamp operating abnormally outputs a sensing signal having a low level ordoes not output a sensing signal since a small quantity of light isincident into the sensor.

When a low level sensing signal is supplied to the voltage cut-offmodule 340 from at least one sensor 360, the voltage cut-off module 340provides the lamp driving module 320 with the voltage cut-off signal 344so that the lamp driving module 320 does not apply the power voltage tothe lamps 100.

When sensing signals having high level are supplied to the voltagecut-Qff module 340 from all of the sensors 360, the voltage cut-offmodule 340 provides the lamp driving module 320 with the voltageapplying signal 342 so that the lamp driving module 320 applies thepower voltage to the lamps 100.

According to the embodiment 3, the embodiment 3 may be adopted when thedistance between the lamp and the sensor is too far or too close for thesensor to exactly detect the turn-on or turn-off state of the lamp inaccordance with photoelectric effect or electromagnetic induction.

Embodiment 1 of Backlight Assembly

FIG. 9 is an exploded perspective view showing a first exemplaryembodiment of a backlight assembly according to the present invention.

Referring to FIG. 9, the backlight assembly 500 includes a lamp assembly200, a lamp driving apparatus 300 and a receiving container 400.

The lamp assembly 200 includes a plurality of lamps 100 and a module 60.

Each of the lamps 100 includes a lamp body 110, a first electrode 120and a second electrode 130. The first electrode 120 is disposed at afirst end of the lamp, and the second electrode 130 is disposed at asecond end of the lamp. For example, the first and second electrode 120and 130 is external electrodes disposed at the external surface of thelamp body 110.

At least two lamps are arranged in parallel. Each of the lamps has alength L1, and the total width of the lamps 100 is W1.

The module 160 is parallel connected to the lamps arranged in parallel.The module 160 includes a first module 140 and a second module 150. Thefirst module 140 includes a first conductive plate 145 and a first clip147. The first clip 147 fixes the first electrodes of the lamps. Thesecond module 150 includes a second conductive plate 155 and a secondclip 157. The second clip 157 fixes the second electrodes of the lamps.The first module 140 is connected to a first power line 149, and thesecond module 150 is connected to a second power line 159.

The receiving container 400 receives the lamp assembly 200. Thereceiving container 400 includes a bottom face 410 and side faces 420.The bottom face 410 and the side face 420 provide enough receiving spaceto receive the lamp assembly 200.

The bottom face 410 has a plurality of openings facing each of the lamps100. Each of the openings has an enough area to pass the light or themagnetic flux generated from the lamps 100 through the openings. Forexample, the openings may be arranged along a straight line on thebottom face 410 of the receiving container 400.

The bottom face 410 includes a first opening 417 and a second opening419. The first power line 149 connected to the first module 145 is drawnout through the first opening 417. The second power line 159 connectedto the second module 150 is drawn out through the second opening 419.

The first power line 149 is connected to a first connection part 380,and the second power line 159 is connected to a second connection part390. The first and second connection parts 380 and 390 are connected tothe lamp driving module 320.

A lamp driving apparatus 300 is disposed an outer surface of the bottomface 410 of the receiving container 400. The lamp driving apparatus 300turns off all of the lamps 100 when a lamp operating abnormally isdetected. The lamp driving apparatus 300 is insulated from the receivingcontainer 400. Especially, when the receiving container 400 comprises aconducting material, the lamp driving apparatus 300 should be completelyinsulated from the receiving container 400. Therefore, a conductivemember may be formed along the circumference of the substrate 310, theconductive member insulate the sensors 330 and the receiving container400.

The lamp driving apparatus 300 includes a substrate 310, sensors 330, alamp driving module 320 and a voltage cut-off module 340.

Each of the sensors 330 is disposed on the substrate 310 to be disposedunder each of the lamps100. The lamp driving module 320 supplies powervoltage to the module 160 of the lamp assembly 200. The voltage cut-offmodule 340 compares a reference signal level and the signal level of thesensing signal outputted from the sensors 330, and provides the lampdriving module 320 with the voltage supply signal or voltage cut-offsignal so that the lamp driving module 320 applies or does not appliesthe power voltage to the lamps 100.

For example, the sensor includes a conductive member for transducing amagnetic flux generated from at least one of the lamps to a currentsignal.

Since the lamp driving apparatus 300 of this embodiment is the same asthat of the embodiment 1 of the lamp driving apparatus, the samereference numerals denote the same elements of the embodiment 1 of thelamp driving apparatus, and thus the detailed descriptions of the sameelements will be omitted.

A reflection plate 460 may be further installed on the bottom face 410of the receiving container 400. The reflection plate 460 reflects thelight generated from the lamps 100.

Embodiment 2 of Backlight Assembly

FIG. 10 is an exploded perspective view showing a second exemplaryembodiment of a backlight assembly according to the present invention.In the embodiment 2 of the backlight assembly, other elements except thereflection plate and sensors are the same as those of the embodiment 1of the backlight assembly, the same reference numerals denote the sameelements of embodiment 1 of the backlight assembly, and thus thedetailed descriptions of the same elements will be omitted.

Referring to FIG. 10, the sensors 350 includes a conductive member 450and an amorphous silicon thin film 352. The amorphous silicon thin film352 is disposed on an upper surface of the conductive member 354. Theamorphous silicon thin film 354 transduces the light generated from thelamps 100 to current by a photoelectric effect.

The reflection plate 460 includes openings 465. The openings 460 formedon the reflection plate 460 allow the light generated from the lamps 100to be incident into the sensors 350. Each of the openings 465 isdisposed under each of the openings 415 formed on the bottom face 410 ofthe receiving container 400.

Embodiment 3 of Backlight Assembly

FIG. 11 is an exploded perspective view showing a third exemplaryembodiment of a backlight assembly according to the present invention.In the embodiment 3 of the backlight assembly, other elements except thereflection plate and sensors are the same as those of the embodiment 1of the backlight assembly, the same reference numerals denote the sameelements of embodiment 1 of the backlight assembly, and thus thedetailed descriptions of the same elements will be omitted.

Referring to FIG. 11, the sensors 360 includes a photoelectric devicefor transducing the light generated from the lamps to current by aphotovoltaic effect. For example, the sensor 360 includes a photodiodeor a phototransistor.

The reflection plate 460 includes openings 465. The openings 460 formedon the reflection plate 460 allow the light generated from the lamps 100to be incident into the sensors 360. Each of the openings 465 isdisposed under each of the openings 415 formed on the bottom face 410 ofthe receiving container 400.

Embodiment of Liquid Crystal Display Device

FIG. 12 is an exploded perspective view showing an example of a liquidcrystal display device according to the present invention.

Referring to FIG. 12, the liquid crystal display device 800 includes abacklight assembly 500 and a liquid crystal display panel 600. Theliquid crystal display device 800 may further includes a chassis 700.

The backlight assembly 500 includes a lamp assembly 200, a lamp drivingapparatus 300, a receiving container 400 and optical plate(s) 490.

The lamp assembly 200 includes lamps 100 and a module 160. The lampassembly 200 described in the embodiments of the lamp driving apparatuswill not be further described below to avoid a redundancy.

The receiving container 400 receives the lamp assembly 200. Thereceiving container 400 includes a bottom face 410 having a plurality ofopenings 415 each of which faces each of the lamps 100. Each of theopenings has an enough area to pass the light or the magnetic fluxgenerated from the lamps 100 through the openings 415.

A lamp driving apparatus 300 is disposed an outer surface of the bottomface 410 of the receiving container 400.

The lamp driving apparatus 300 includes a substrate 310, sensors 330, alamp driving module 320 and a voltage cut-off module 340.

Each of the sensors 330 is disposed on the substrate 310 to be disposedunder each of the lamps 100. For example, the sensor includes aconductive member for transducing a magnetic flux generated from atleast one of the lamps to a current signal. The sensor may include aphotoelectric sensor for transducing a light generated from at least oneof the lamps to a current signal by a photoelectric effect. The sensormay include a photoelectric device for transducing a light generatedfrom at least one of the lamps to a current signal by a photovoltaiceffect.

The lamp driving apparatus 300 includes a voltage cut-off module 340.The voltage cut-off module 340 provides the lamp driving module 320 withthe voltage supply signal when all of the signal levels of sensingsignals outputted from the sensors are larger than the reference signallevels. Accordingly, all of the lamps 100 are turned on by the powervoltage applied from the lamp driving module 320.

The voltage cut-off module 340 provides the lamp driving module 320 withthe voltage cut-off signal when at least one signal levels of thesensing signals are smaller than the reference signal levels.Accordingly, all of the lamps 100 are turned off by the lamp drivingmodule 320.

A reflection plate 460 may be further installed between the bottom face410 of the receiving container 400 and the lamp assembly 200. Thereflection plate 460 reflects the light generated from the lamps 100toward the liquid crystal display panel 600 so as to enhance displayquality.

The liquid crystal display panel 600 is received in the receivingcontainer 400. The liquid crystal display panel 600 displays an imageusing the light generating from the lamp assembly 200.

The liquid crystal display panel 600 includes a thin film transistor(TFT) substrate 610, a liquid crystal layer 620 and a color filtersubstrate 630.

The TFT substrate 610 includes a plurality of thin film transistors andpixel electrodes. The thin film transistors are arranged in a matrixshape on a first transparent substrate.

The color filter substrate 630 faces the TFT substrate 610, and includesa common electrode and color filters formed on a second transparentsubstrate. The common electrode is formed on an entire surface of thesecond transparent substrate on which the color filters are formed, andfaces the pixel electrode. The color filter are disposed between thecommon electrode and the second transparent substrate, and disposed overeach of the pixel electrodes.

The liquid crystal is disposed between the TFT substrate 610 and thecolor filter substrate 630. An electric field is formed between thepixel electrode and the common electrode and the amount of the lightpassing through the liquid crystal layer is regulated. The lightgenerated from the lamp assembly 200 passes through the liquid crystallayer and an image is displayed.

While the exemplary embodiments of the present invention and itsadvantages have been described in detail, it should be understood thatvarious changes, substitutions and alterations can be made hereinwithout departing from the scope of the invention as defined by appendedclaims.

1. A liquid crystal display device comprising: a backlight assemblyincluding i) a lamp assembly including a plurality of lamps arranged inparallel, each of the lamps having a first electrode formed at a firstend and a second electrode formed at a second end, the lamp assemblyproviding the lamps with a power voltage to turn on or Win off thelamps, ii) a receiving container to receive the lamp assembly, thereceiving container having a plurality of openings facing each of thelamps, iii) a lamp driving device including iii-1) a substrate facingthe receiving container, iii-2) a lamp driving module providing thelamps with the power voltage, iii-3) a plurality of sensors, disposed onthe substrate to face the lamps, to detect an operation state of thelamps and to output a plurality of sensing signals, iii-4) a voltagecut-off module, disposed on the substrate, to compare the sensingsignals with a predetermined reference signal, the voltage cut-offmodule providing the lamp driving module with a voltage cut-off signalto prevent the lamp driving module from providing the lamps with thepower voltage when at least one of the sensing signals has an amplitudesmaller than the reference signal; and a liquid crystal display panelassembly, mounted on the receiving container, to display an image usinga light generating from the lamps.
 2. A backlight assembly comprising: alamp assembly including a plurality of lamps arranged in parallel, eachof the lamps having a first electrode formed at a first end and a secondelectrode formed at a second end, the lamp assembly providing the lampswith a power voltage to turn on or turn off the lamps; a receivingcontainer that receives the lamp assembly, the receiving containerhaving a plurality of openings facing each of the lamps; a lamp drivingdevice including i) a substrate facing the receiving container, ii) alamp driving module providing the lamps with the power voltage, iii) aplurality of sensors, disposed on the substrate to face the lamps, todetect an operation state of the lamps to output a plurality of sensingsignals, iv) a voltage cut-off module, disposed on the substrate, tocompare the sensing signals with a predetermined reference signal, thevoltage cut-off module providing the lamp driving module with a voltagecut-off signal to prevent the lamp driving module from providing thelamps with the power voltage when at least one of the sensing signalshas an amplitude smaller than the reference signal.
 3. The backlightassembly of claim 2, wherein the lamp assembly further comprises a firstmodule and a second module through which the power voltage is suppliedto the lamps, the first electrodes of each of the lamps are connected tothe first module, the second electrodes of each of the lamps areconnected to the second module, and the first and second module areconnected to the lamp driving module.
 4. The backlight assembly of claim2, wherein the sensors includes a conductive member that transduces amagnetic flux generated from at least one of the lamps to a currentsignal to output the sensing signal.
 5. The backlight assembly of claim2, further comprising a reflection plate, disposed between the lamps andthe receiving container, to reflect a light incident into the receivingcontainer toward the lamps.
 6. The backlight assembly of claim 2,wherein the sensors are electrically insulated by an insulation member.7. The backlight assembly of claim 6, wherein the insulation member isdisposed on the substrate and insulates the sensors from the receivingcontainer.
 8. The backlight assembly of claim 2, wherein the sensorsdetect the operation state of the lamps through the openings of thereceiving container, and each of the sensors are disposed under each ofthe openings.
 9. The backlight assembly of claim 2, wherein the sensorsare disposed on a first surface of the receiving container, and the lampdriving module and the voltage cut-off module are disposed on a secondsurface of the receiving container, the first surface facing the lamps,the second surface facing the first surface.
 10. The backlight assemblyof claim 2, wherein the substrate of the lamp driving device is disposedcorresponding to the first electrode of each of the lamps.
 11. A lampdriving apparatus comprising: a plurality of lamps arranged in parallel;a substrate facing the lamps; a lamp driving module providing the lampswith a power voltage; a plurality of sensors, disposed on the substrateto face the lamps, to detect an operation state of the lamps and tooutput a plurality of sensing signals; and a voltage cut-off module,disposed on the substrate, to compare the sensing signals with apredetermined reference signal, the voltage cut-off module providing thelamp driving module with a voltage cut-off signal to prevent the lampdriving module from providing the lamps with the power voltage when atleast one of the sensing signals has an amplitude smaller than thereference signal.
 12. The lamp driving apparatus of claim 11, whereinthe sensors includes a conductive member that transduces a magnetic fluxgenerated from at least one of the lamps to a current signal to outputthe sensing signal.
 13. The lamp driving apparatus of claim 12, whereinthe conductive member comprises a copper plate.
 14. The lamp drivingapparatus of claim 11, wherein each of the sensors is spaced apart fromeach of the lamps by a distance in a range from about 3mm to about 5 mm.15. The lamp driving apparatus of claim 14, wherein the substratefurther includes a distance regulation member to regulate the distancebetween the sensors and the lamps.
 16. The lamp driving apparatus ofclaim 11, wherein the sensing signal is a first current signal and thereference signal is a second current signal.
 17. The lamp drivingapparatus of claim 11, wherein the substrate further includes analarming device that alarms in response to the voltage cut-off signal.18. The lamp driving apparatus of claim 11, wherein the sensor includesa photoelectric sensor that transduces a light generated from at leastone of the lamps to a current signal based on a photoelectric effect tooutput the sensing signal.
 19. The lamp driving apparatus of claim 18,wherein the photoelectric sensor includes a conductive member and anamorphous silicon thin film, the amorphous silicon thin film formed onthe conductive member to face the lamps.
 20. The lamp driving apparatusof claim 18, wherein the sensor further includes a light interferenceprotection member that selectively receives the light generated from thelamps.
 21. The lamp driving apparatus of claim 11, wherein the sensorincludes a photoelectric device that transduces a light generated fromat least one of the lamps to a current signal based on a photovoltaiceffect to output the sensing signal.
 22. The lamp driving apparatus ofclaim 18, wherein the photoelectric device includes a photodiode or aphototransistor, the photodiode or the phototransistor having a thinfilm shape.
 23. The lamp driving apparatus of claim 21, wherein thesensor further includes a light interference protection member thatselectively receives the light generated from the lamps.